The present invention relates to a memory device and related control method, and more particularly to a memory device with reduced half-select-disturbance, and a related method.
In a memory such as a static random access memory, a logic value can be written in or read out from a memory cell of the memory. When a logic value is written to the memory cell, the voltage level of the word line coupled to the memory cell is charged to a high voltage level to turn on the pass transistors of the memory cell. Then, if the bit value being written is logic 1, the voltage level of a first bit line coupled to the memory cell is charged to the high voltage level and the voltage level of a second bit line coupled to the memory cell is discharged to a low voltage level; if the bit value being written is logic 0, the voltage level of the first bit line is discharged to the low voltage level and the voltage level of the second bit line is charged to the high voltage level. Accordingly, the logic value is written into the memory cell of the memory by complementing the voltage levels of the first bit line and the second bit line coupled to the memory cell. However, when the voltage level of the word line coupled to the memory cell is charged to the high voltage level, all of the pass transistors of the other memory cells coupled to the word line are also turned on, and the memory cells that are coupled to the word line but not coupled to the first bit line and the second bit line may suffer from a disturb phenomenon. Therefore, the logic values stored in the other memory cells could be changed, which is called the half-select-disturb phenomenon. To reduce this half-select-disturb phenomenon, the pass transistors need to be sized down. However, to improve write margin and write-in speed, the pass transistors need to be sized up. In other words, there is a trade-off when choosing the sizes of the pass transistors of the conventional memory cell. How to improve the stability and the accessing speed of the static random access memory cell is becoming a critical problem in this field.